Back to EveryPatent.com
United States Patent |
5,095,617
|
Costa
,   et al.
|
March 17, 1992
|
Method for forming a drain assembly
Abstract
A method of forming a drain assembly 30 for a case 26 is disclosed. Various
construction details are developed for minimizing the radial profile and
facilitating assembly to an opening in the case while blocking the passage
of flames from the exterior to the interior. In one embodiment, the method
of forming the drain assembly 30 includes disposing a cover 42 facing one
side of the case which has a passage 48 therethrough, disposing a plate 58
having a passage 62 on the other side of the case, and disposing a baffle
66 in the opening to block flames from passing between the cover side of
the case and the plate side of the case.
Inventors:
|
Costa; Mark W. (Storrs, CT);
Shach; Steven P. (Beltsville, MD)
|
Assignee:
|
United Technologies Corporation (Hartford, CT)
|
Appl. No.:
|
626115 |
Filed:
|
December 4, 1990 |
Current U.S. Class: |
29/889.2; 29/513; 29/888; 60/39.094 |
Intern'l Class: |
F02G 003/00 |
Field of Search: |
29/889.2,888,513
60/39.094,39.08,39.11
270/374
|
References Cited
U.S. Patent Documents
1865319 | Jun., 1932 | Jensen.
| |
3199716 | Aug., 1965 | Price | 220/44.
|
4163366 | Aug., 1979 | Kent | 60/266.
|
Primary Examiner: Cuda; Irene
Attorney, Agent or Firm: Fleischhauer; Gene D.
Parent Case Text
This is a division of co-pending application Ser. No. 07/316,901 filed on
Feb. 28, 1989.
Claims
We claim:
1. A method of forming a drain assembly for an engine case having a first
side and a second side facing in opposite directions and an opening in the
case which extends from the first side to the second side, comprising:
disposing a cover on the first side of the case such that the cover engages
the case, the cover including at least one first passage which extends
through the cover to the opening;
disposing a plate on the second side of the engine case which faces the
engine case to form a drain chamber therebetween and providing at least
one second passage through the plate to the drain chamber;
disposing a baffle in the opening between the cover and the plate, and
providing the baffle with a plurality of openings for placing the first
passages in flow communication with the drain chamber;
attaching the baffle to the plate and to the cover to urge the plate and
the cover toward the outer case.
2. The method of forming the drain assembly of claim 1 which further
includes forming tabs on the baffle which extend away from the plate and
attaching the baffle to the plate prior to disposing the baffle in the
opening, inserting the tabs through the cover and bending the tabs over to
urge the cover and the plate toward the engine case, thereby securing the
drain assembly to the engine case.
3. The method of forming a drain assembly of claim 1 wherein the step of
disposing the plate on the first side of the case includes the step of
orienting the cover such that each first passage extends parallel to the
first side and the step of disposing the baffle includes the step of
extending the baffle laterally with respect to the passages to block line
of sight communication of the passages with the drain chamber and spacing
the opening in the baffle from the inlet passages so as to not interrupt
the blockage of line of sight communication between the inlet passages and
the drain chamber.
4. The method of forming the drain assembly of claim 1 which includes the
step of disposing a resilient material between the plate and the second
side, the resilient material extending circumferentially about the outlet
passage.
5. The method of forming the drain assembly of claim 4 wherein the gas
turbine engine has a secondary flowpath for working medium gases and
wherein the step of disposing the plate on the second side of the engine
case includes orienting the drain assembly such that the plate faces and
is adjacent to the secondary flowpath for working medium gases.
Description
TECHNICAL FIELD
This invention relates to axial flow, gas turbine engines and more
particularly to a drain assembly for the case of such an engine. This
invention was developed in the field of aircraft gas turbine engines and
has application to other structures employing a drain assembly.
BACKGROUND OF THE INVENTION
One example of a gas turbine engine is a turbofan, gas turbine engine of
the type used to propel aircraft. The turbofan engine has a primary
flowpath for working medium gases which is annular in shape. The annular
flowpath extends through a compression section, a combustion section, and
a turbine section. The engine has a rotor assembly which extends axially
through these sections of the engine. A stator assembly, which includes an
engine case, extends axially through the engine outwardly of the rotor
assembly to bound the working medium flowpath and to support the rotor
assembly of the engine.
A secondary flowpath for working medium gases is annular in shape and
extends axially rearward through the engine outwardly of the primary
flowpath. The stator assembly includes a portion of the engine case which
provides an inner boundary to the secondary flowpath and a portion of a
fan duct which provides an outer boundary to the flowpath.
During engine operation, fuel is supplied to the combustion section where
it is burned to produce energy. The energy is used to develop a propulsive
thrust and to drive the rotor assembly about an axis of rotation.
Hydraulic and lubricating fluids are supplied to other sections of the
engine for hydraulic actuators and for lubricating moving components.
The fuel, hydraulic and lubricating systems may develop small, intermittent
leaks which occur during engine operation. As a result, fluids may
accumulate at very low rates at the bottom of the engine on the interior
of the engine case. Because these fluids are flammable, it is desirable to
drain the fluids via an opening in the engine case into the secondary
flowpath. The large volume of rushing gases in the secondary flowpath
sweeps away the small amount of fluid draining from the case during engine
operation at a flammable fluid to air ratio which does not support
combustion.
One disadvantage of a drain opening is that the opening provides a path for
flames to the inside should a fire occur outside the engine or a path for
flames to the outside should a fire occur on the inside of the engine.
Accordingly, it is desirable to provide a device for draining fluids from
the case that blocks flames from passing through the device from the
inside of the case to the outside or from the outside to the inside.
One example of a device which might be used in other fields is shown in
U.S. Pat. No. 1,960,259 entitled "Safety Device" which was issued to
Wyman. In the Wyman construction, a plug threadably engages a case. The
case has an axially extending inlet passage, an axially extending outlet
passage, and an axially extending apparatus for blocking flames which
extends from the inlet to the outlet passage. The apparatus includes a
number of axially spaced disks. Each disk has a chordal segment cut away
to provide an opening which axially faces the adjacent disks. This forms a
tortuous path from the inlet to the outlet which is easily followed by the
draining fluid while providing an effective device for blocking the
passage of flames.
It is important in gas turbine engines to avoid using a drain assembly
which intrudes into the secondary flowpath because the intrusion disrupts
the flow in the secondary flowpath with a concomitant decrease in
aerodynamic performance. In addition, it is important to minimize how far
the device extends into the engine interior because of close clearances
between the engine case and structures on the interior of the engine. The
clearances are kept close to minimize the radial profile of the engine
which decreases drag on the engine during operative conditions.
Accordingly, scientists and engineers working under the direction of
Applicants, assignee are working to develop a drain assembly for an engine
case, which has a low profile to fit in the clearance between the engine
case and structure inwardly of the engine case, and which allows fluids to
freely flow from the interior while providing a barrier to flames.
DISCLOSURE OF THE INVENTION
According to the present invention, a drain assembly having a chamber for
collecting fluid prior to discharge has an inlet passage and an outlet
passage which are perpendicular to each other, a baffle between the
passages which blocks the one of the passages from line of sight
communication with the chamber and a manifold which extends laterally with
respect to one of the passages to provide a passage for fluid and a
tortuous path for flame.
In accordance with one embodiment of the present invention, the drain
assembly extends through an opening in the engine case of a gas turbine
engine and includes a cover on one side of the case bounding the inlet
passage and a plate on the other side of the case bounding the outlet
passage; the cover and plate are urged toward the case by the baffle with
a resilient compound disposed between the drain assembly and the case to
provide sealing and to damp vibrations in the drain assembly.
In accordance with one detailed embodiment of the present invention, the
inlet has a plurality of inlet passages and the baffle has a plurality of
tabs which extend outwardly at each inlet passage to block line of sight
communication with the chamber and to engage the cover to urge the cover
toward the engine case.
A primary feature of the present invention is a drain assembly for an
opening having a cover on one side of a structure, (such as an engine case
for a gas turbine engine) and a plate on the other side of the structure
leaving a drain chamber therebetween. Another feature is a baffle disposed
in the opening between the cover and the plate to bound the drain chamber.
In one embodiment, the baffle extends laterally to block line of sight
communication between an inlet passage and the drain chamber. Another
feature is a manifold between the cover and the baffle which extends from
the inlet passage to the drain chamber. In a more detailed embodiment, the
baffle is attached to the plate and is attached to the cover to urge the
cover and the plate toward the engine case. The baffle has a plurality of
tabs which extend through the cover and are bent over during assembly to
retain both the plate and the cover. Another feature is a resilient
material disposed between the drain assembly and the engine case.
A principal advantage of the present invention is the low profile of a
flame proof drain assembly for a case which results from the plate and
cover construction with the cover having passage for fluid which extends
parallel to the case. Another advantage is the ease of fabricability
resulting from the use of a simple three element structure to provide a
flameproof drain to an opening in a case. Still another advantage is the
simplicity of the structure and the ability of the structure to adapt to
casings having different thicknesses. In one detailed embodiment, an
advantage the fatigue life of the structure which results from using
sealing material to reduce vibrations in the drain assembly.
The foregoing features and advantages of the present invention will become
more apparent in light of the following detailed description of the best
mode of carrying out the invention and in the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side elevation view of an axial flow, gas turbine engine with a
portion of the fan duct broken away to show a secondary flowpath and a
portion of a drain assembly.
FIG. 2 is a partial perspective view of a portion of the engine case and an
exploded perspective view of the drain assembly.
FIG. 3 is a side elevation cross-sectional view of the engine case and the
drain assembly.
FIG. 4 is a view from above of the drain assembly shown in FIG. 3 with a
portion of the cover broken away to show an inlet passage and a portion of
a baffle.
FIG. 5 is a partial perspective view in schematic fashion showing the
relationship of the structure to a flowpath for draining fluid which
extends through the drain assembly.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a side elevation view of a turbofan gas turbine engine 10 which
has axis of rotation R. The engine has a compression section 12, a
combustion section 14, and a turbine section 16. An annular flowpath 18
for primary working medium gases extends axially through the sections of
the engine. A portion of the flowpath is shown by the dotted lines. A
secondary flowpath 20 for working medium gases extends axially through the
engine outwardly of the primary flowpath.
A stator assembly 22 extends axially through the engine to bound the
secondary flowpath. The stator assembly includes a fan duct 24 and an
engine case 26. A case is any protective covering, sheath or housing
whether on the interior of a structure or not. The engine case 26 is
closely adjacent to internal structure 28 to minimize the radial profile
of the engine case. For example, the clearance between the structure and
the engine case might be as small as one-half of an inch (0.50"). A drain
assembly 30 is disposed between the internal structure and the bottom of
the engine case. The drain assembly places the interior of the engine case
in flow communication with the secondary flowpath for working medium gases
20. The drain assembly is exaggerated in size for clarity.
FIG. 2 is a partial perspective view of the engine case 26 and an exploded
view of the drain assembly 30. The engine case 26 has a first side 32
facing the interior of the engine case and a second side 34 facing the
secondary flowpath. A drain opening 36 in the engine case extends between
the first side and the second side. The opening is cylindrical and is
disposed about the axis A. The opening might be cylindrical, rectangular
or any other shape in which case the axis A would be equally spaced from
opposite surfaces extending through the engine case. The drain assembly
may be formed of any ductile, corrosion resistant material which is
compatible with the adjacent environment. One material which is acceptable
is a stainless steel alloy as set forth in Aerospace Material
Specification (AMS) 5510.
The drain assembly 30 includes a cylindrical plug assembly 38 and a
circular cover 42. The circular cover has a circular edge 44. A rim
section 46 extends circumferentially about the cover and inwardly from the
edge. The rim section engages the first side of the engine case. The rim
section includes a plurality of (that is, two or more) inlet passages 48
which extend parallel to the case. The inlet passages are spaced
circumferentially one from the other and extend radially inward from the
edge. The inlet passages are bounded in part by the inside case. Not using
additional cover material to bound the passage at this location reduces
the radial height of the drain assembly. In alternate constructions, the
cover might entirely bound the inlet passages, especially where radial
height is not of significant importance.
The rim section 46 includes a raised central section 52. A wall 54 extends
axially inward to the rim section and circumferentially between the inlet
passages. The raised central section includes four circumferentially
extending slots 56 which are each circumferentially aligned with an
associated inlet passage 48.
The cylindrical plug assembly 38 has a plate 58 facing the second side 34
of the engine case. The plate has an outlet passage 62 which extends in a
direction which is substantially perpendicular to the inlet passage 48. A
resilient seal member 64 extends circumferentially about the outlet
passage and disposed between the plate and the engine case. The resilient
seal member is formed of an adhesive/sealant such as a flame resistant,
silicone rubber. One suitable material is DAPCOCAST No. 18-4 which is
available from D Aircraft Products, Inc., Anaheim, Calif. 92807.
The cylindrical plug assembly 38 includes an integral baffle member 66
having an opening 71 in flow communication with the opening 62. The baffle
is attached to the plate 58 by brazing or any other suitable bonding
technique or by mechanical fasteners such as screws, rivets, or any other
suitable fastener. In some embodiments, the baffle member may not be
attached to the plate 58 or it may be formed as one piece with the plate.
Each baffle member has a plurality of tabs 68. Each tab extends axially
from the baffle and is aligned with an associated hole 56 in the cover.
The tabs are circumferentially spaced one from the other leaving an
opening 72 therebetween.
FIG. 3 is a side elevation, cross-sectional view of the drain assembly 30
shown in FIG. 2 in the assembled condition. The drain assembly has a drain
chamber 74 disposed on the interior of the assembly. The drain chamber
extends between the cover 42 and the plug assembly 38. The baffle 66
bounds the drain chamber.
As shown in FIG. 3, each tab 68 of the baffle is circumferentially aligned
with and radially faces an associated inlet passage 48 of the cover. The
tab extends axially through the cover and is bent over in the assembled
condition to attach the baffle and the plate to the cover. The tab 68
extends laterally with respect to the inlet passage and to the wall 54 to
block line of sight communication from the inlet passage to the drain
chamber 74. The tab is spaced radially from the wall leaving a
circumferentially or laterally extending manifold 76 between the wall and
the baffle. The opening 72 between each pair of tabs is not radially
aligned with the inlet passage and places the manifold in flow
communication with the drain chamber 74.
As shown in FIG. 3, the resilient, elastomeric material 64 is compressed
during assembly and provides a seal between the baffle 66 and the opening
36 in the wall of the case. The baffle is preferably formed of a diameter
slightly smaller than the opening 36 to minimize the gap G between the
baffle and the opening. The gap G is exaggerated for clarity. As will be
realized, the resilient material might extend directly between the baffle
and the opening in those embodiments where the gap G would permit the
resilient material to extend into that location. In addition, the
resilient material might be disposed between the cover and the first side
of the case for additional damping but this would add to the radial height
of the construction. Alternatively, the drain assembly might be oriented
so that the cover is disposed on the outside 34 of the case and the plate
disposed in the inside of the case.
FIG. 4 is a top view of the cover 42 shown in FIG. 2 and FIG. 3 showing the
relationship of the baffle 66 and its tab 68 to the wall 54 and the inlet
passage 48 in the cover. As shown, the tab 68 radially faces and is
circumferentially aligned with the inlet passage 48.
FIG. 5 is a partial perspective view of the drain assembly 28 shown in FIG.
2 showing the relationship of the flowpath 78 for drain fluid, each of
which extends through an inlet passage 48 and the opening 72 between the
adjacent tabs 68. As can be seen, each flowpath enters parallel to the
engine casing, is diverted laterally by the baffle, enters the drain
chamber 74 where it makes a right angle turn toward the openings 62,71 in
the baffle and the plate which form the outlet passage for the plug
assembly. The flowpaths 78 extend through the openings into the secondary
flowpath 20.
As shown by FIG. 5, the fluid follows a tortuous path through the drain
assembly. The tortuous path prevents flames from either side of the case
from passing through the drain assembly. In the unlikely event that a fire
does occur in the engine case, and there is fluid draining from the engine
case, the low radial height of the cover and the inlet passages ensures
that the inlet passages are covered with fluid. In addition to the path
through the drain providing a flameproof barrier by reason of the
inability of the flame to change directions, the fluid flowing through the
drain which fills the drain will further block the flames from passing
through the case.
An advantage is the ease of fabricability which results from using a two
piece assembly by forming the baffle and plate as a single unitary plug
assembly. During construction of the engine, this permits inserting the
core assembly through the opening 36 in the case. The cover 42 is disposed
on the other side of the case. Each tab 68 engages an associated opening
56 in the cover 42. The tabs are bent over to secure the baffle to the
cover, compressing the resilient silicone, elastomeric material between
the plate and the engine case. The tabs alone allow the drain assembly to
accommodate different thicknesses of the engine case while still
permitting the drain assembly to provide a baffled flowpath.
Another advantage is the simplicity of forming the components of the
structure which results from combining the retention device with the
baffle in a single device by having the tabs extend radially outward at a
location where the tabs interrupt line of sight communication between the
inlet passage 48 and the drain chamber 74.
Although the invention has been shown and described with respect to
detailed embodiments thereof, it should be understood by those skilled in
the art that various changes in form and detail thereof may be made
without departing from the spirit and scope of the claimed invention:
Top